First of all, your kernel is more than recent enough, so stop using radeonfb.
But other than that, it seem everything is working correctly, startx doesn't do anything noteworthy on its own, you need some clients (a window manager at very least).
If the mouse cursor doesn't move, then you failed to post a large enough portion of the xorg log - pastebin a complete one.
It might be a matter of udev not marking the input devices correctly - check the nodes with 'udevadm info'.

On a not quite related note: 'root=/dev/hda3' says you're at least one migration short.

OK, I performed a make pmac32_defconfig to configure the kernel initially, so I believe that is what selected radeonfb, since Ì don't remember specifically selecting it.
What other option do I have? What should I be using? I tried fbdev too, same result, but that might be because of a kernel module conflict with radeonfb... Not sure, so feel free to tell me which options I should set/clear..

As an aside, I tried unselecting things I knew for sure were not needed, but that ends up making the machine boot without a working network card for some reason...

Gnome and GDM are installed, and letting GDM start up by itself results in the same black screen.

About the cursor: There is no mouse cursor, it is a black text-mode screen, with a text-mode cursor, the one just before switching into graphics mode.

That IS the complete xorg log I posted. I did edit out the canned supported graphic card models listing because I thought it wasn't relevant. If it appears incomplete, it is because X is locking up as it generates the log and the last line posted is the last line X emitted.

I also tried X -configure but I read that that is no longer supported? Here is its output, in case I am wrong about that:

Quote:

_XSERVTransSocketOpenCOTSServer: Unable to open socket for inet6
_XSERVTransOpen: transport open failed for inet6/tiny:0
XSERVTransMakeAllCOTSServerListeners: failed to open listener for inet6

About hda vs sda: I know what you mean but as I mentioned, it is the initial kernel config that makes it that way because no sdx devices exist once the kernel has booted. If you have a tip on how to fix that one or a link to info on how to resolve that, please post it.

OK, so you've got a broken kernel...well, actually a not fully functional one, but same difference.

Pastebin your kernel config - perhaps somebody will find time to point out most of the things, that are wrong with it.
For the moment, according to the udevadm output (not quite the one I asked for, but good enough), you don't have a mouse.

If I log in as root through ssh and type pidof X while terminal 1 is apparently locked-up running X, it returns nothing. I take it that means X is not running?

Correct. This then mean your X isn't locked-up, just that your console now is black (and by the error you report i suppose the radeon driver is bitching your card).

I know 0 to radeon, and 0 to mac, so i couldn't help you for that part, but i were you :
NeddySeagoon has shown many many times to (many many) users how to setup a radeon card, dig radeon thread with his name in it, your answer is there i'm 99.9% sure.
I've saw him so many times saying it that i could have learned it, if i didn't learned before to never brought again an ati card

CONFIG_KERNEL_XZ=y
CONFIG_DEVTMPFS=y
CONFIG_DEVTMPFS_MOUNT=y
CONFIG_IDE not set
CONFIG_ATA=y
CONFIG_LEGACY_PTYS not set
CONFIG_HPET=y (if valid for the platform)
CONFIG_DRM_RADEON_KMS=y
CONFIG_FB_RADEON not set
CONFIG_SND_HRTIMER=y
CONFIG_SND_SUPPORT_OLD_API not set
CONFIG_USB_DEVICEFS not set
CONFIG_USB_HIDDEV=y
CONFIG_EXT2_FS not set
CONFIG_EXT3_FS not set
CONFIG_EXT4_USE_FOR_EXT23=y
CONFIG_EXT4_FS_POSIX_ACL=y
CONFIG_TMPFS_POSIX_ACL=y
CONFIG_FANOTIFY=y
CONFIG_FANOTIFY_ACCESS_PERMISSIONS=y
CONFIG_TMPFS_POSIX_ACL=y
CONFIG_TMPFS_XATTR=y

It's VIDEO_CARDS and 'radeon' is fine in mesa 7 (mesa 8 is a bit more fine grained, but the value is still valid there). For something as old as 9200, gallium is pointless - it needs to be at least r300.
The missing symbol is (or at least should be) present in extensions/libdri.so (it belongs to xorg-server), add USE=libkms just in case.
Check 'eselect opengl' and 'eselect mesa'.

It's VIDEO_CARDS and 'radeon' is fine in mesa 7 (mesa 8 is a bit more fine grained, but the value is still valid there). For something as old as 9200, gallium is pointless - it needs to be at least r300.
The missing symbol is (or at least should be) present in extensions/libdri.so (it belongs to xorg-server), add USE=libkms just in case.
Check 'eselect opengl' and 'eselect mesa'.

OK, following your recommendations, X now starts!

One detail; there is only the x11-xorg implementation of OpenGL listed when I do eselect opengl list.

One thing which is different now is that before, the xorg.conf I used to enable the mac to use a television (with a dvi-to-svideo adapter) as a display doesn't work properly... The resolution is still the proper one for the TV (800x600) but now the refresh rate causes the television to display a garbled, snowy image.

I suspect it is probably the modeline support changing that has done that.

CONFIG_KERNEL_XZ=y
CONFIG_DEVTMPFS=y
CONFIG_DEVTMPFS_MOUNT=y
CONFIG_IDE not set
CONFIG_ATA=y
CONFIG_LEGACY_PTYS not set
CONFIG_HPET=y (if valid for the platform)
CONFIG_DRM_RADEON_KMS=y
CONFIG_FB_RADEON not set
CONFIG_SND_HRTIMER=y
CONFIG_SND_SUPPORT_OLD_API not set
CONFIG_USB_DEVICEFS not set
CONFIG_USB_HIDDEV=y
CONFIG_EXT2_FS not set
CONFIG_EXT3_FS not set
CONFIG_EXT4_USE_FOR_EXT23=y
CONFIG_EXT4_FS_POSIX_ACL=y
CONFIG_TMPFS_POSIX_ACL=y
CONFIG_FANOTIFY=y
CONFIG_FANOTIFY_ACCESS_PERMISSIONS=y
CONFIG_TMPFS_POSIX_ACL=y
CONFIG_TMPFS_XATTR=y